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BQ76952: Problem with establishing Comunication

vinod sharma
Prodigy 20 points
Part Number: BQ76952

Hi TI Team,

I am using BQ76952 in BMS project. I have assembled a custom BMS PCB. I am trying to establish the communication between MCU and AFE for the first time. When I am powering up, I have provided the 48V to pack pin, and Vbat pin,and I am getting the voltage at REG18 pin 1.8V

Observing the waveform on I2C line, CLK is coming properly from MCU side @ 400kHz and on executing first sub command of 0x10 NACK is coming on the SDA line. After that neither data is coming nor the communication is setting up. This should be ACK but I am unable to establish this connection.

Now I am attaching the waveform and PCB layout for your reference.

Let me know what is going wrong.

 

Thanks,

Vinod

  • 0
    TI__Mastermind 25605 points

    Hi Vinod,

    It looks like the clock is being held low by something in between the transmissions. It could be that the BQ76952 is clock-stretching.

    Note that it is required to have an MCU that supports clock-stretching when communicating with the BQ769x2 devices. Could you check that the MCU you are using supports this?

    Regards,

    Max Verboncoeur